title: Natural history of asymptomatic unruptured cerebral aneurysms evaluated at CT angiography: growth and rupture incidence and correlation with epidemiologic risk factors.
abstract: OBJECTIVE
  To characterize the relationship between aneurysm size and epidemiologic risk factors with growth and rupture by using computed tomographic (CT) angiography.
  
  
  METHODS
  In this HIPAA-compliant, institutional review board approved study, patients with known asymptomatic unruptured intracerebral aneurysms were followed up longitudinally with CT angiographic examinations. Growth was defined as an increase in one or more dimensions above the measurement error, and at least 5% volume by using the ABC/2 method. Associations of epidemiologic factors with aneurysm growth and rupture were analyzed by using logistic regression analysis. Intra- and interobserver agreement coefficients for dimension, volume, and growth were evaluated by using the Pearson correlation coefficient and difference of means with 95% confidence intervals, the agreement statistic, and the McNemar χ(2).
  
  
  RESULTS
  Patients (n = 165) with aneurysms (n = 258) had a mean follow-up time of 2.24 years from time of diagnosis. Forty-six of 258 (18%) aneurysms in 38 patients grew larger. Spontaneous rupture occurred in four of 228 (1.8%) intradural aneurysms of average size (6.2 mm). Risk of aneurysm rupture per patient-year was 2.4% (95% CI: 0.5%, 7.12%) with growth and 0.2% (95% CI: 0.006%, 1.22%) without growth (P = .034). There was a 12-fold higher risk of rupture for growing aneurysms (P < .002), with high intra- and interobserver correlation coefficients for size, volume, and growth. Tobacco smoking (3.806, one degree of freedom; P < .015,) and initial size (5.895, two degrees of freedom; P < .051) were independent covariates, predicting 78.4% of growing aneurysms.
  
  
  CONCLUSIONS
  These results support imaging follow-up of all patients with aneurysms, including those whose aneurysms are smaller than the current 7-mm treatment threshold. Aneurysm growth, size, and smoking were associated with increased rupture risk.
authors.affiliation: Departments of Radiological Sciences and Neurosurgery, University of California, Ronald Reagan UCLA Medical Center, 757 Westwood Plaza, Suite 1621A, Los Angeles, CA, 90095-1721.
authors.forename: J Pablo
authors.initials: JP
authors.lastname: Villablanca
authors.forename: Gary R
authors.initials: GR
authors.lastname: Duckwiler
authors.forename: Reza
authors.initials: R
authors.lastname: Jahan
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tateshima
authors.forename: Neil A
authors.initials: NA
authors.lastname: Martin
authors.forename: John
authors.initials: J
authors.lastname: Frazee
authors.forename: Nestor R
authors.initials: NR
authors.lastname: Gonzalez
authors.forename: James
authors.initials: J
authors.lastname: Sayre
authors.forename: Fernando V
authors.initials: FV
authors.lastname: Vinuela
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D002533:Cerebral Angiography / Q000706:statistics & numerical data*; D018450:Disease Progression; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*